Effects of Different Nitrogen Applications and Field Return Depth on the Diversity and Function of Bacteria in Returned Straw in Cold Paddy Fields

This study investigates the degradation characteristics, bacterial community structure, and mechanism of rice straw under different levels nitrogen (N) application depths return 1-mature-winter tillage in paddy fields a cold zone from perspective biodegradation by using nylon mesh bag situ culture method. Paludibacteraceae Ruminococcaceae were dominant bacteria process, their abundance decreased with increasing depth return. The activities extracellular enzymes associated C-cycle (α-glucosidase, β-glucosidase, β-cellobiosidase, β-xylosidase) generally higher than those other functional enzymes, enzyme increased middle late stages (104 d). At an N rate 110–150 kg hm−2, potential functionality soil showed quadratic trend application. When full amount was returned to field, there significant spatial heterogeneity functionality. Our results that most optimum 140 while best level (0–15 cm) observed layer zone.